Environmental Engineering Reference
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50 μm
25 μm
Figure 4.41
Meridion
. Fan-shaped colonies of this
colonial diatom. Prepared slide.
(b) Cells do not have silica walls. Main stor-
age product starch. . . ..................
81
77
(76) (a) Cells cuneate in shape, so when
joined together form a fan-shaped colony
...............................
Meridion
The cells, or frustules, of
Meridion
are het-
eropolar in girdle view and isobilateral in
valve view. Within the frustule are thickened
transparent costae and on the frustule surface
fine parallel striae. A pseudoraphe is present
on both valves. Individual cells (24-45 μm
long) are usually united to form fan-shaped
colonies. If growth of the colony is vigor-
ous then a flat spiral-shaped colony devel-
ops. Grows attached to surfaces in shallow
waters. Bacillariophyta. Plate XI. Fig. 4.41.
50 μm
Figure 4.40
Volvox.
Top:Imagefocussedontheequa-
torial cells of the spherical colony. Numerous zygotes
(arrows) are present in the central cavity. Bottom: Indian
ink preparation, showing limits of colony. Flagella not
visible in these bright field images.
(b) Cells form stellate or zig-zag colonies
.....................................
78
76
(69) (a) Cells with silica walls which often bear
distinct markings. Storage products mainly
oils that can often be seen as small globules
withinthecell,notstarch..............
77
78
(77) (a) Frustules swollen at each end to form
a knob, the inner one at the hub of the
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